1. Field of Invention
This invention relates to a method and apparatus for machine implemented analysis of the effects of various events upon the compliance of a complex process plant with technical specifications. More particularly, it relates to a method and apparatus which combines fault tree analysis with efficient data base management techniques and man-machine interface design to determine compliance with limiting conditions of operation and system operability in such complex processes as nuclear power plants.
2. Background Information
As technological advances produce more complex automated processes, the burden placed upon the operator in monitoring and managing such processes, especially under abnormal conditions, has become increasingly heavier. Consequently, it has become ever more important that the operator be provided with adequate information to make informed decisions in a form which is easily understandable, even under conditions of stress which might arise with the occurrence of an unexpected event.
A typical complex automated process is a nuclear power plant. The operation of such plants is governed by very strict regulatory requirements including compliance with technical specifications (tech specs). These tech specs are designed to assure that nuclear plant operations are consistent with, and supported by, the plant safety analysis. In other words, they define an envelope in which the plant should be operated so as to assure public safety. However, the tech specs have evolved into what is today a very complex set of requirements that may be difficult to interpret and manage proficiently. In addition, the tech specs contain poorly identified, interrelated requirements which may lead to unintentional noncompliance with the provisions of one spec when responding to another.
There is a definite need therefore, for a system which will aid the plant operator in assuming compliance with the tech specs. This includes aid in determining compliance with limiting conditions of operations (LCOs) and determining the operability of certain systems. It is also important for the operator to be aware of the events which resulted in non-compliance with an LCO or the inoperability of a system.
Accordingly, it is a primary object of the invention to provide a method and apparatus for aiding the operator of a complex process plant in assuring compliance of the operation of the plant with technical specifications, including in the case of a nuclear power plant, limiting conditions of operation.
It is another object of the invention to provide such a method and apparatus which takes into account the affects of the inoperability of a component or system on multiple technical specifications;
It is still another object of the invention to satisfy the previous objects with a method and apparatus which utilizes operability trees to determine compliance with technical specifications and the operability of systems;
it is yet another object of the invention to satisfy the latter object with a computer based method and apparatus which utilizes efficient data base management techniques to search the thousands of cutsets in the operability trees required for a complex process plant, including techniques to reduce the processing time required to find all the members of multiple event cutsets.
It is also an object of the invention to provide a method and apparatus in accordance with the previous objects which is capable of generating for the user an output identifying the events which led to a non-compliance with tech specs.